This invention concerns coolant systems, and more particularly systems adapted to return collected contaminated coolant from a number of machine tools, filter the returned coolant and supply filtered coolant back to each machine tool via a supply pipe network.
Heretofore, coolant containing machining chips and other contaminants has typically been returned to a filtration unit by a below grade velocity trench, which receives coolant from each of a number of machine tools. Flow nozzles direct jets of clean coolant into the trench in a return direction to carry the chips and other solid debris along the trench to a filtration unit.
There has recently developed a trend towards above grade installations since below grade trenches, typically steel lined, can develop hard to detect leaks by the wearing action of the filtered solids scouring the surface, this leakage possibly contaminating the groundwater below.
Leak proof liners for the trenches are typically quite costly to provide so that above grade pressurized return flow coolant arrangements have been employed for returning the contaminated coolant to the filter. In these arrangements, a separate pump at each machine pumps the coolant into an overhead collection header.
This arrangement has also proved costly due to the need for a large number of pumps, one for each machine, particularly since the pump must have a design which accommodates machine chips, etc., without clogging.
It is the object of the present invention to provide an above grade coolant return system and method for a plurality of machine tools which does not require the large number of costly pumps previously required.